1. Field of the Invention
The present invention relates to a substrate processing apparatus for performing a cleaning process, an etching process and other processes upon substrates such as semiconductor substrates, glass substrates for a liquid crystal display device, glass substrates for a photomask and the like by dipping the substrates in a processing liquid.
2. Description of the Background Art
In the process of manufacturing substrates, a substrate processing apparatus is used which processes the substrates by dipping the substrates in a processing liquid stored in a processing bath. FIG. 18 is a view showing an example of a background art substrate processing apparatus 100. As shown in FIG. 18, the background art substrate processing apparatus 100 includes a processing bath 110 for storing a processing liquid therein, and causes the processing liquid to overflow from a top portion of the processing bath 110 while discharging the processing liquid from discharge nozzles 113 provided in a bottom portion of the processing bath 110 to supply the processing liquid to around substrates W, thereby processing the substrates W.
In particular, a substrate processing apparatus of what is called a one-bath type discharges a plurality of types of processing liquids such as an etchant, a cleaning liquid, deionized water and the like in sequential order from the discharge nozzles 113. Such a substrate processing apparatus stores the plurality of types of processing liquids in sequential order within the processing bath 110 to thereby perform a plurality of types of processes in sequential order upon the substrates W.
As shown in FIG. 18, the discharge nozzles 113 in the background art substrate processing apparatus 100 are designed to discharge the processing liquid toward the substrates W within the processing bath 110. Thus, the processing liquid discharged from the discharge nozzles 113 forms relatively high-speed liquid flows within the processing bath 110 and is agitated all over the inside of the processing bath 110. Such a conventional form of discharge, however, is intended to agitate the processing liquid all over the inside of the processing bath 110, and is not capable of efficiently draining a used processing liquid from the processing bath 110 to replace the used processing liquid with a new processing liquid.
In such a background art substrate processing apparatus 100, foreign substances such as particles, if contained within the processing bath 110, are also agitated together with the processing liquid within the processing bath 110. Thus, the background art substrate processing apparatus 100 is not capable of rapidly remove the foreign substances contained within the processing bath 110 from the processing bath 110. Such foreign substances are deposited onto the surfaces of the substrates W being processed to give rise to apprehensions about the contamination of the substrates W and about the processing failures of the substrates W. In particular, when an acid chemical liquid is used as the processing liquid or when substrates W having hydrophobic surfaces are used, the foreign substances such as particles are prone to adhere to the surfaces of the substrates W to make the above-mentioned problem more serious.
For the substrate processing apparatus of the one-bath type, it is desired in some cases to uniformly process the substrates W as in an etching process, and it is desired in other cases to efficiently replace a processing liquid stored within the processing bath with another processing liquid. For the uniform processing of the substrates W, it is desirable to form a relatively high-speed liquid flow within the processing bath, thereby making the concentration of the processing liquid stored within the processing bath uniform. For the efficient replacement of the processing liquid stored within the processing bath with another processing liquid, on the other hand, it is desirable to form a relatively low-speed liquid flow within the processing bath, thereby discharging the processing liquid in such a manner as to force the processing liquid outwardly from the top portion of the processing bath.
The background art substrate processing apparatus, however, is configured to discharge the processing liquid from the pair of discharge nozzles 113 toward the inside of the processing bath 110, as described above. Because of such a configuration, it is difficult to form different liquid flows within the processing bath 110 depending on processing conditions. The background art substrate processing apparatus is not capable of satisfying both the requirement for improvements in processing uniformity of the processing liquid and the requirement for efficient replacement of the processing liquid stored within the processing bath with another processing liquid.